Carbamate-substituted pyrazolopyridines

ABSTRACT

The present invention relates to compounds which stimulate soluble guanylate cyclase, to the preparation thereof and to the use thereof as medicaments, in particular as medicaments for the treatment of cardiovascular disorders and/or sexual dysfunction.

The present invention relates to compounds which stimulate solubleguanylate cyclase, to the preparation thereof and to the use thereof asmedicaments, in particular as medicaments for the treatment ofcardiovascular disorders and/or sexual dysfunction.

One of the most important cellular transmission systems in mammaliancells is cyclic guanosine monophosphate (cGMP). Together with nitricoxide (NO), which is released from the endothelium and transmitshormonal and mechanical signals, it forms the NO/cGMP system. Guanylatecyclases catalyse the biosynthesis of cGMP from guanosine triphosphate(GTP). The representatives of this family disclosed to date can bedivided both according to structural features and according to the typeof ligands into two groups: the particulate guanylate cyclases which canbe stimulated by natriuretic peptides, and the soluble guanylatecyclases which can be stimulated by NO. The soluble guanylate cyclasesconsist of two subunits and very probably contain one haem perheterodimer, which is part of the regulatory site. The latter is ofcentral importance for the mechanism of activation. NO is able to bindto the iron atom of haem and thus markedly increase the activity of theenzyme. Haem-free preparations cannot, by contrast, be stimulated by NO.CO is also able to attach to the central iron atom of haem, but thestimulation by CO is distinctly less than that by NO.

Through the production of cGMP and the regulation, resulting therefrom,of phosphodiesterases, ion channels and protein kinases, guanylatecyclase plays a crucial part in various physiological process, inparticular in the relaxation and proliferation of smooth muscle cells,in platelet aggregation and adhesion and in neuronal signaltransmission, and in disorders caused by an impairment of theaforementioned processes. Under pathophysiological conditions, theNO/cGMP system may be suppressed, which may lead for example to highblood pressure, platelet activation, increased cellular proliferation,endothelial dysfunction, atherosclerosis, angina pectoris, heartfailure, thromboses, stroke, sexual dysfunction and myocardialinfarction.

A possible way of treating such disorders which is independent of NO andaims at influencing the cGMP signal pathway in organisms is a promisingapproach because of the high efficiency and few side effects which areto be expected.

Compounds, such as organic nitrates, whose effect is based on NO have todate been exclusively used for the therapeutic stimulation of solubleguanylate cyclase. NO is produced by bioconversion and activates solubleguanylate cyclase by attaching to the central iron atom of haem. Besidesthe side effects, the development of tolerance is one of the crucialdisadvantages of this mode of treatment.

Some substances which directly stimulate guanylate cyclase, i.e. withoutprevious release of NO, have been described in recent years, such as,for example, 3-(5′-hydroxymethyl-2′-furyl)-1-benzylindazole (YC-1, Wu etal., Blood 84 (1994), 4226; Mülsch et al., Brit. J. Pharmacol. 120(1997), 681), fatty acids (Goldberg et al, J. Biol. Chem. 252 (1977),1279), diphenyliodonium hexafluorophosphate (Pettibone et al., Eur. J.Pharmacol. 116 (1985), 307), isoliquiritigenin (Yu et. al., Brit. J.Pharmacol. 114 (1995), 1587) and various substituted pyrazolederivatives (WO 98/16223).

In addition, WO 98/16507, WO 98/23619, WO 00/06567, WO 00/06568, WO00/06569, WO 00/21954 WO 02/42299, WO 02/42300, WO 02/42301, WO02/42302, WO 02/092596 and WO 03/004503 describe pyrazolopyridinederivatives as stimulators of soluble guanylate cyclase. Also describedinter alia therein are pyrazolopyridines having a pyrimidine residue inposition 3. Compounds of this type have very high in vitro activity inrelation to stimulating soluble guanylate cyclase. However, it hasemerged that these compounds have disadvantages in respect of their invivo properties such as, for example, their behaviour in the liver,their pharmacokinetic behaviour, their dose-response relation or theirmetabolic pathway.

It was therefore the object of the present invention to provide furtherpyrazolopyridine derivatives which act as stimulators of solubleguanylate cyclase but do not have the disadvantages detailed above, ofthe compounds from the prior art.

This object is achieved by the compounds according to claim 1 of theinvention. This new class of pyrazolopyridine derivatives isdistinguished by having in position 3 a pyrimidine residue which has aparticular subsitution pattern, namely a carbamate residue in position 5of the pyrimidine ring, and an amino group in position 4 of thepyrimidine ring.

The present invention specifically relates to compounds of the formula(I).

in which

-   R¹ is —NR³C(═O)OR⁴,-   R² is hydrogen or NH₂,-   R³ is hydrogen or (C₁–C₄)-alkyl,-   R⁴ is (C₁–C₆)-alkyl,    and salts, isomers and hydrates thereof.

Preference is given to compounds of the formula (I) in which

-   R¹ is —NR³C(═O)OR⁴,-   R² is hydrogen or NH₂,-   R³ is (C₁–C₄)-alkyl,-   R⁴ is (C₁–C₄)-alkyl,    and salts, isomers and hydrates thereof.

Particular preference is given to compounds of the formula (I) in which

-   R¹ is —NR³C(═O)OR⁴,-   R² is NH₂,-   R³ is methyl or ethyl,-   R⁴ is methyl, ethyl or isopropyl,    and salts, isomers and hydrates thereof.

Especial preference is given to the compoundmethyl-4,6-diamino-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-5-pyrimidinyl(methyl)carbamatefrom Example 8:

The compounds according to the invention of the formula (I) may also bein the form of their salts. Mention may generally be made here of saltswith organic or inorganic bases or acids.

Physiologically acceptable salts are preferred for the purposes of thepresent invention. Physiologically acceptable salts of the compoundsaccording to the invention may be salts of the substances according tothe invention with mineral acids, carboxylic acids or sulphonic acids.Particularly preferred examples are salts with hydrochloric acid,hydrobromic acid, sulphuric acid, phosphoric acid, methanesulphonicacid, ethanesulphonic acid, p-toluenesulphonic acid, benzenesulphonicacid, naphthaline-disulphonic acid, acetic acid, propionic acid, lacticacid, tartaric acid, citric acid, fumaric acid, maleic acid or benzoicacid.

Physiologically acceptable salts may likewise be metal or ammonium saltsof the compounds according to the invention having a free carboxylgroup. Particularly preferred examples are sodium, potassium, magnesiumor calcium salts, and ammonium salts derived from ammonia or organicamines such as, for example, ethylamine, di- or triethylamine, di- ortriethanol amine, dicyclohexylamine, dimethylaminoethanol, arginine,lysine or ethylenediamine.

The compounds according to the invention may exist in tautomeric forms.This is known to the skilled person, and the invention likewiseencompasses such forms.

The compounds according to the invention may furthermore be in the formof their possible hydrates.

Alkyl is a linear or branched alkyl radical having, as a rule, 1 to 6,preferably 1 to 4, particularly preferably 1 to 3, carbon atoms, by wayof example and preferably methyl, ethyl, n-propyl, isopropyl,tert-butyl, n-pentyl and n-hexyl.

Halogen is for the purposes of the invention fluorine, chlorine, bromineand iodine

The present invention also relates to a process for preparing thecompounds according to the invention of the formula (I). These can beprepared

-   [A] by reacting compounds of the formula (Ia)

-   -   in which    -   R⁴ is as defined above,    -   with compounds of the formula (II)        R³—X¹  (II),    -   in which    -   R³ is as defined above, and    -   X¹ is a leaving group such as, for example, halogen, preferably        iodine, or mesylate,    -   where appropriate in an organic solvent with cooling to give        compounds of the formula (I),        or

-   [B] by reacting the compound of the formula (III)

-   -   with compounds of the formula (IV)

-   -   in which    -   R⁴ is as defined above,    -   where appropriate in an organic solvent to give compounds of the        formula (Ia),        or

-   [C] by reacting the compound of the formula (V)

-   -   with compounds of the formula (VI)

-   -   in which    -   R³ and R⁴ are as defined above,    -   where appropriate in an organic solvent with heating to give        compounds of the formula (Ib)

-   -   in which    -   R³ and R⁴ are as defined above.

The compounds of the formulae (II) and (IV) are commercially availableor known from the literature or can be prepared in a manner known to theskilled person.

The compound of the formula (III) can be prepared as shown in thefollowing reaction scheme:

Compound (III) is obtainable in a two-stage synthesis by reactingcompound (V) with compound (VII) to give compound (VIII) in accordancewith process step [C] and subsequently hydrogenating compound (VIII)with aqueous Raney nickel. The hydrogenation can be carried out in anorganic solvent, for example dimethylformamide, preferably underelevated pressure, for example under 50 to 70 bar, preferably under 65bar, stirring the reaction solution for several hours, for example for22 hours, at elevated temperature, for example at 40 to 80° C.,preferably at 60° C. to 65° C.

The compound (VII) can be prepared in analogy to L. F. Cavalieri, J. F.Tanker, A. Bendich, J. Am. Chem. Soc., 1949, 71, 533.

The compound (V) can be prepared as shown in the following reactionscheme:

compound (V) is obtainable in a multistage synthesis from the sodiumsalt of ethyl cyanopyruvate, which is known from the literature (Borscheand Manteuffel, Liebigs. Ann. Chem. 1934, 512, 97). Reaction thereofwith 2-fluorobenzylhydrazine while heating under a protective gasatmosphere in an inert solvent such as dioxane results in ethyl5-amino-1-(2-fluorobenzyl)pyrazole-3-carboxylate, which can be cyclizedby reaction with dimethylaminoacrolein in acidic medium under aprotective gas atmosphere and heating to give the corresponding pyridinederivative. This pyridine derivative, ethyl1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-carboxylate, is convertedby a multistage sequence consisting of conversion of the ester withammonia into the corresponding amine, dehydration with a dehydratingagent such as trifluoroacetic anhydride to give the correspondingnitrile derivative, reacting the nitrile derivative with sodium ethoxideand finally reaction with ammonium chloride into the compound (V).

The compounds of the formula (VI) can be synthesized by methods known tothe skilled person from the corresponding carbamates by reaction withethyl formate. The carbamates can be prepared in analogy to Q. Li, D. T.Chu, A. Claiborne, C. S. Cooper, C. M. Lee, J. Med. Chem. 39 (1996)3070–3088.

Reaction of the compounds of the formulae (Ia) and (II) to givecompounds of the formula (I) can be carried out by using the reactantsin equimolar amounts in an organic solvent, for exampledimethylformamide or tetrahydrofuran, preferably in the presence of 1 to2 equivalents, preferably 1.1 to 1.5 equivalents, of a base such as, forexample, sodium hydride or sodium N,N-bistrimethylsilylamide, preferablyunder atmospheric pressure and with stirring of the reaction solutionfor a few hours, for example for 1 hour, with cooling, for example at−10° C. to room temperature, preferably at 0° C.

Reaction of the compounds of the formulae (III) and (IV) to give thecompounds of the formula (Ia) can be carried out by using the reactantsin equimolar amounts in an organic solvent, for example an organic base,preferably pyridine, preferably under atmospheric pressure and withstirring of the reaction solution for several hours, for example for 12hours, at 0° C. to room temperature, preferably at room temperature.

Reaction of compounds of the formulae (V) and (VI) to give compounds ofthe formula (Ib) or of compounds of the formulae (V) and (VII) to givecompounds of the formula (VIII) can be carried out by using thereactants in equimolar amounts or with use of the compound of theformula (VI) in slight excess in an organic solvent such as, forexample, in a hydrocarbon such as toluene or xylene or inN,N-dimethylformamide, preferably in the presence of 2–3 equivalents,preferably 2 equivalents, of a base such as, for example, triethylamineor sodium methanolate, preferably under atmospheric pressure and withstirring of the reaction solution for several hours, for example for 9hours, at elevated temperature, for example at 80–160° C., preferably at100–150° C., in particular at 110° C.

The compounds according to the invention of the formula (I) show avaluable range of pharmacological effects which could not have beenpredicted.

The compounds according to the invention of the formula (I) bring aboutvasorelaxation and an inhibition of platelet aggregation and lead to areduction in blood pressure and an increase in coronary blood flow.These effects are mediated by direct stimulation of soluble guanylatecyclase and an intracellular increase in cGMP. In addition, thecompounds according to the invention of the formula (I) enhance theeffect of substances which increase the cGMP level, such as, forexample, EDRF (endothelium derived relaxing factor), NO donors,protoporphyrin IX, arachidonic acid or phenylhydrazine derivatives.

They can therefore be employed in medicaments for the treatment ofcardiovascular disorders such as, for example, for the treatment of highblood pressure and heart failure, stable and unstable angina pectoris,peripheral and cardiac vascular disorders, of arrhythmias, for thetreatment of thromboembolic disorders and ischaemias such as myocardialinfarction, stroke, transient ischaemic attacks, disturbances ofperipheral blood flow, prevention of restenoses as after thrombolysistherapies, percutaneous transluminal angioplasties (PTAs), percutaneoustransluminal coronary angioplasties (PTCAs), bypass and for thetreatment of arteriosclerosis, asthmatic disorders and diseases of theurogenital system such as, for example, prostate hypertrophy, erectiledysfunction, female sexual dysfunction, osteoporosis, glaucoma,pulmonary hypertension, gastroparesis and incontinence.

The compounds according to the invention of the formula (I) are alsosuitable for controlling central nervous system diseases characterizedby disturbances of the NO/cGMP system. They are suitable in particularfor improving perception, concentration, learning or memory aftercognitive impairments like those occurring in particular in associationwith situations/diseases/syndromes such as mild cognitive impairment,age-associated learning and memory impairments, age-associated memoryloss, vascular dementia, craniocerebral trauma, stroke, dementiaoccuring after strokes (post stroke dementia), post-traumatic brainsyndrome, general concentration impairments, concentration impairmentsin children with learning and memory problems, Alzheimer's disease, Lewybody dementia, dementia with degeneration of the frontal lobes includingPick's syndrome, Parkinson's disease, progressive nuclear palsy,dementia with corticobasal degeneration, amyotrophic lateral sclerosis(ALS), Huntington's disease, multiple sclerosis, thalamic degeneration,Creutzfeld-Jakob dementia, HIV dementia, schizophrenia with dementia orKorsakoff's psychosis. They are also suitable for the treatment ofcentral nervous system disorders such as states of anxiety, tension anddepression, CNS-related sexual dysfunctions and sleep disturbances, andfor controlling pathological disturbances of the intake of food,stimulants and addictive substances.

The compounds according to the invention of the formula (I) arefurthermore also suitable for controlling cerebral blood flow and thusrepresent effective agents for controlling migraine.

The compounds according to the invention of the formula (I) are alsosuitable for the prophylaxis and control of the sequelae of cerebralinfarctions such as stroke, cerebral ischaemias and craniocerebraltrauma. They can likewise be employed for controlling states of pain.

In addition, the compounds according to the invention of the formula (I)have an anti-inflammatory effect and can therefore be employed asanti-inflammatory agents.

Furthermore the present invention also encompasses the combination of atleast one compound according to the invention of the formula (I) withone or more organic nitrates or NO donors.

Organic nitrates and NO donors for the purposes of the invention aregenerally substances which display their therapeutic effect via releaseof NO or NO species. Mention may be made by way of example andpreferably of: sodium nitroprusside, nitroglycerine, isosorbidedinitrate, isosorbide mononitrate, molsidomine and SIN-1.

In addition, the present invention also encompasses the combination withone or more compounds which inhibit breakdown of cyclic guanosinemonophosphate (cGMP). These are preferably inhibitors ofphosphodiesterases 1, 2 and 5; nomenclature of Beavo and Reifsnyder(1990), TiPS 11 pp. 150 to 155. Particularly preferred in thisconnection are inhibitors of phosphodiesterase 5 (PDE V inhibitors),especially one of the compounds sildenafil (Viagra™, EP-A 0 463 756, WO94/28902), vardenafil (WO 99/24433) or tadalafil (WO 95/19978). Theseinhibitors potentiate the effect of the compounds according to theinvention, and the desired pharmacological effect is increased.

Biological Investigations

Vasorelaxant Effect in Vitro

Rabbits are stunned by a blow to the back of the neck and areexsanguinated. The aorta is removed, freed of adherent tissue anddivided into rings 1.5 mm wide, which are put singly under tension in 5ml organ baths containing carbogen-gassed Krebs-Henseleit solution at37° C. with the following composition (mM): NaCl:119; KCl:4.8;CaCl₂×2H₂O:1; MgSO₄×7H₂O:1.4; KH₂PO₄:1.2; NaHCO₃:25; Glucose:10. Theforce of contraction is detected with Statham UC2 cells, amplified anddigitized via A/D converters (DAS-1802 HC, Keithley Instruments Munich)and recorded in parallel on chart recorders. A contraction is generatedby adding phenylephrine to the bath cumulatively in increasingconcentration. After several control cycles, the substance to beinvestigated is investigated in each further run in increasing dosage ineach case, and the height of the contraction is compared with the heightof the contraction reached in the last preceding run. The concentrationnecessary to reduce the height of the control value by 50% (IC₅₀) iscalculated from this. The standard application volume is 5 μl, and theDMSO content in the bath solution corresponds to 0.1%.

The IC₅₀ for the compound of Example 1 is 670 nM, and the correspondingvalue for the compound of Example 8 is 500 nM.

Rabbit Model

Adult male chinchilla rabbits weighing 3–5 kg are adapted to being keptsingly for several days after delivery. They have free access to waterand can take feed for two hours a day. The animals are kept in a10/14-hour day/night rhythm (light on from 8.00 h), and the roomtemperature is 22–24° C.

Three to six animals are used in each treatment group and are weighedimmediately before the start of the test. For the i.v. administration,the substances are dissolved in Transcutol (GATTEFOSSE GmbH) and dilutedin the ratio 3/7 with a 20% strength Cremophor solution (Cremophor(BASF), water). A volume of 0.5 ml/kg is injected into the ear vein.Water-soluble substances are injected in 0.9% sodium chloride solution.

For oral administration, the test substances are dissolved in a6:10:9.69 glycerol:water:polyethylene glycol mixture and administered bygavage in a volume of 1 ml/kg.

Under resting conditions, the rabbit penis is invisible in the pubicregion and is completely covered by the penis skin. The erection isassessed by measuring the length of the protruding penis with a slidecalliper. The measurement is carried out 5, 10, 15, 30, 45, 60 and 120minutes after administration of the substance and, after oraladministration, additionally after 3, 4, 5 and 6 hours. The animals arefor this purpose removed from the cage each time, held firmly by theneck fur and the rear paws, turned on their backs and measured.Corresponding solvent controls are carried out. (Compare reference: E.Bischoff, K. Schneider, Int. J. of Impotence Res. 2001, 13, 230–235; E.Bischoff, U. Niewoehner, H. Haning, M. Es Sayed, T. Schenke, K. H.Schlemmer, The Journal of Urology, 2001, 165, 1316–1318; E. Bischoff,Int. J. Impotence Res. 2001, 13, 146–148).

The minimal effective dose of the compound of Example 8 on oraladministration is 0.03 mg/kg (with simultaneous administration of 0.2mg/kg i.v. sodium nitroprusside SNP).

Determination of Pharmacokinetic Parameters after Intravenous and OralAdministration

The substance to be investigated is administered intravenously assolution to animals (e.g. mice, rats, dogs), and oral administrationtakes place as solution or suspension by gavage. After administration ofthe substance, blood is taken from the animals at fixed times and isheparinized, and then plasma is obtained therefrom by centrifugation.The substance is quantified analytically in the plasma by LC/MS/MS. Theplasma concentration/time courses found in this way are used tocalculate the pharmacokinetic parameters by means of a validatedpharmacokinetic computer programme.

After oral administration of 0.3 and 1.0 mg/kg (as solution inSolutol:EtOH:Wasser 1:1:8) to rats, the compound of Example 8 shows thefollowing plasma concentrations (AUC):

-   AUCstand (0.3 mg/kg)=0.326 [kg*h/L]-   AUCstand (1.0 mg/kg)=0.548 [kg*h/L]    Inhibition of Cytochrome P450 Enzymes

The potential for inhibition of P-450 isoenzymes which are important formetabolism is investigated automatically in a 96-well format. Twodifferent assays are used for this.

In the assay based on the formation of fluorescent metabolites,recombinant enzymes (e.g. CYP1A2, 2C8, 2C9, 2C19, 2D6 or 3A4) and ingeneral substrates containing fluorescein or coumarin partial structuresare employed. In each case one substrate concentration and 8concentrations of the potential inhibitor are used. After incubationwith the particular recombinant CYP enzyme, a fluorescence reader isused to measure the extent of fluorescent metabolites compared with thecontrol (without inhibitor), and an IC₅₀ is calculated [Anal. Biochem.248, 188 (1997)].

In the 2nd assay, human liver microsomes are used as enzyme source, andthe CYP isoform-selective substrates used are phenacetin (CYP1A2),diclofenac (CYP2C9), dextromethorphan (CYP2D6) and midazolam (CYP3A4).The formation of the particular metabolite is measured using LC-MS/MS.Assuming that inhibition is competitive, K_(i) values are calculatedfrom the reduction in metabolite formation compared with the control (1substrate and 3 inhibitor concentrations).

Induction of Cytochrome P450 Enzymes in Human Liver Cell Cultures

To investigate the potential for side effects of the substancesaccording to the invention in relation to induction of cytochrome P450enzymes, primary human hepatocytes are cultured with a cell density of2.5×10⁵ cells between two layers of collagen in 24-well microtitreplates at 37° C. with 5% CO₂ for 8 days. The cell culture medium ischanged each day.

After 48 hours in culture, the hepatocytes are treated with differentconcentrations of the test substances, comparing with the inducersrifampicin (RIF; 50 μM), omeprazole (OME; 100 μM) and phenobarbital (PB;2 mM), in duplicate determination for 5 days. The final concentrationsof the test substances are 0.01–10 μg/ml.

The inductive effect of the test substances on the cytochrome (CYP) P450enzymes 1A2, 2B6, 2C19 and 3A4 is determined by adding the substrates7-ethoxyresorufin (CYP1A2), [¹⁴C]-S-mephenytoin (CYP2B6 and 2C19) and[¹⁴C]-testosterone (CYP3A4) to the cell cultures on day 8. The inductivepotential of the test substances is found from the activities, measuredin this way, of CYP1A2, 2B6, 2C19 and 3A4 enzymes of treated cellscompared with untreated cells. Table 1 below shows the results of thecompound of Example 8 compared with the inducers RIF, PB and OME:

TABLE 1 Inductive effect on liver enzymic activities in human hepatocytecultures after incubation for 8 days (standardized) Concentra- tionCYP1A2 CYP2B6 CYP2C19 CYP3A4 Control 0 1.0 1.0 1.0 1.0 RIF 50 μM n.d.5.15 15.21 9.15 PB 2000 μM n.d. 14.69 4.00 6.70 OME 100 μM 28.57 1.541.61 1.45 Example 8 0.01 μg/ml 0.76 1.92 1.30 1.37 0.1 μg/ml 0.70 1.621.30 1.60 1.0 μg/ml 0.90 1.85 1.12 1.51 10 μg/ml 1.38 2.54 1.97 3.47n.d. = not determined

The present invention further relates to medicaments which comprise atleast one compound according to the invention, preferably together withone or more pharmacologically acceptable excipients or carriers, and tothe use thereof for the aforementioned purposes.

The active ingredient may have systemic and/or local effects. For thispurpose, it can be administered in a suitable way such as, for example,oral, parenteral, pulmonary, nasal, sublingual, lingual, buccal, rectal,transdermal, conjunctival, topical or as implant.

The active ingredient can be administered in administration formssuitable for these administration routes.

Suitable for oral administration are known administration forms whichdeliver the active ingredient rapidly and/or in a modified manner, suchas, for example, tablets (uncoated and coated tablets, e.g. tabletsprovided with enteric coatings or film-coated tablets), capsules,sugar-coated tablets, granules, pellets, powders, emulsions,suspensions, solutions and aerosols.

Parenteral administration can take place with avoidance of an absorptionstep (intravenous, intraarterial, intracardiac, intraspinal orintralumbar) or with inclusion of an absorption (intramuscular,subcutaneous, intracutaneous, percutaneous, or intraperitoneal).Administration forms suitable for parenteral administration are, interalia, preparations for injection and infusion in the form of solutions,suspensions, emulsions, lyophilizates and sterile powders.

Suitable for the other routes of administration are, for example,pharmaceutical forms for inhalation (inter alia powder inhalers,nebulizers), nasal drops/solutions, sprays; tablets or capsules forlingual, sublingual or buccal administration, suppositories,preparations for the ears and eyes, vaginal capsules, aqueoussuspensions (lotions, shaking mixtures), lipophilic suspensions,ointments, creams, milk, pastes, dusting powders or implants, such as,for example, stents.

The active ingredients can be converted in a manner known per se intothe stated administration forms. This takes place with use of inertnon-toxic, pharmaceutically suitable excipients. These include, interalia, carriers (for example microcrystalline cellulose), solvents (forexample liquid polyethylene glycols), emulsifiers (for example sodiumdodecyl sulphate), dispersants (for example polyvinylpyrrolidone),synthetic and natural biopolymers (for example albumin), stabilizers(for example antioxidants such as ascorbic acid), colourings (forexample inorganic pigments such as iron oxides) or masking flavoursand/or odours. The active ingredient can, where appropriate, be presentalso in microencapsulated form in one or more of the carriers indicatedabove.

The therapeutically effective compound of the formula (I) should bepresent in the pharmaceutical preparations detailed above in aconcentration of about 0.1 to 99.5, preferably of about 0.5 to 95, % byweight of the complete mixture.

The pharmaceutical preparations detailed above may, apart from thecompound according to the invention of the formula (I) also containother active pharmaceutical ingredients.

It has generally proved to be advantageous both in human and inveterinary medicine to administer the active ingredient according to theinvention in total amounts of about 0.001 to about 50, preferably 0.001to 10, mg/kg of body weight every 24 hours, where appropriate in theform of a plurality of single doses, to achieve the desired results. Asingle dose contains the active ingredient according to the inventionpreferably in amounts of about 0.001 to about 30, in particular 0.001 to3, mg/kg of body weight.

The present invention is explained in more detail below by means ofnon-restrictive preferred examples. Unless indicated elsewhere, allquantitative data relate to percentages by weight. Solvent ratios,dilution ratios and concentration data for liquid/liquid solutionsrelate in each case to volume.

Abbreviations: ACN acetonitrile BABA n-butyl acetate/n-butanol/glacialacetic acid/phosphate buffer pH 6 (50:9:25.15; org. phase) conc.concentrated DCI direct chemical ionization (in MS) DCM dichloromethaneDIEA N,N-diisopropylethylamine DMSO dimethyl sulphoxide DMFN,N-dimethylformamide EA ethyl acetate EI electron impact ionization (inMS) ESI electrospray ionization (in MS) h hour HPLC high pressure, highperformance liquid chromatography LC-MS coupled liquidchromatography/mass spectroscopy LDA lithium diisopropylamide MCPBAm-chloroperoxybenzoic acid m.p. melting point MS mass spectroscopy NMRnuclear magnetic resonance spectroscopy R_(f) retention index (in TLC)RP-HPLC reverse phase HPLC RT room temperature R_(t) retention time (inHPLC) sat. saturated THF tetrahydrofuran TLC thin layer chromatographyMobile Phases for Thin-layer Chromatography:

-   T1 E1: toluene/ethyl acetate (1:1)-   T1 EtOH1: toluene/ethanol (1:1)-   C1 E1: cyclohexane/ethyl acetate (1:1)-   C1 E2: cyclohexane/ethyl acetate (1:2)    LCMS and HPLC Methods:    Method 1 (LCMS)-   Instrument: Micromass Platform LCZ, HP1100; column: Symmetry C18, 50    mm×2.1 mm, 3.5 μm; eluent A: acetonitrile+0.1% formic acid, eluent    B: water+0.1% formic acid; gradient: 0.0 min 10% A→4.0 min 90% A→6.0    min 90% A; oven: 40° C.; flow rate: 0.5 ml/min; UV detection:    208–400 nm.    Method 2 (LCMS)-   Instrument: Micromass Quattro LCZ, HP1100; column: Symmetry C18, 50    mm×2.1 mm, 3.5 μm; eluent A: acetonitrile+0.1% formic acid, eluent    B: water+0.1% formic acid; gradient: 0.0 min 10% A→4.0 min 90% A→6.0    min 90% A; oven: 40° C.; flow rate: 0.5 ml/min; UV detection:    208–400 nm.    Method 3 (LCMS)-   Instrument: Waters Alliance 2790 LC; column: Symmetry C18, 50 mm×2.1    mm, 3.5 μm; eluent A: water+0.1% formic acid, eluent B:    acetonitrile+0.1% formic acid; gradient: 0.0 min 5% B→5.0 min 10%    B→6.0 min 10% B; temperature: 50° C.; flow rate: 1.0 ml/min; UV    detection: 210 nm.    Method 4 (HPLC)-   Instrument: HP 1100 with DAD; column: Kromasil RP-18, 60 mm×2 mm,    3.5 μm; eluent: A=5 ml of HClO₄/l of H₂O, B=ACN; gradient: 0 min 2%    B, 0.5 min 2% B, 4.5 min 90% B, 6.5 min 90% B; flow rate: 0.75    ml/min; temp.: 30° C.; detection UV 210 nm.    Preparative RP-HPLC-   Column: YMC gel; eluent: acetonitrile/water (gradient); flow rate:    50 ml/min; temp.: 25° C.; detection UV 210 nm.    Starting Compounds:

EXAMPLE 1A Ethyl 5-amino-1-(2-fluorobenzyl)pyrazole-3-carboxylate

111.75 g (75 ml, 0.98 mol) of trifluoroacetic acid are added to 100 g(0.613 mol) of sodium salt of ethyl cyanopyruvate (prepared in analogyto Borsche and Manteuffel, Liebigs Ann. 1934, 512, 97) in 2.5 l ofdioxane under argon with efficient stirring at room temperature, and themixture is stirred for 10 minutes during which much of the precursordissolves. Then 85.93 g (0.613 mol) of 2-fluorobenzylhydrazine areadded, and the mixture is heated under reflux overnight. After cooling,the crystals of sodium trifluoroacetate which have separated out arefiltered off with suction and washed with dioxane, and the solution isreacted further as it is.

EXAMPLE 2A Ethyl1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridine-3-carboxylate

The solution obtained from Example 1A is mixed with 61.25 ml (60.77 g,0.613 mol) of dimethylaminoacrolein and 56.28 ml (83.88 g, 0.736 mol) oftrifluoroacetic acid and boiled under argon for 3 days. The solvent isthen evaporated in vacuo, and the residue is added to 2 l of water andextracted three times with 1 l of ethyl acetate each time. The combinedorganic phases are dried with magnesium sulphate and concentrated in arotary evaporator. Chromatography is carried out on 2.5 kg of silicagel, eluting with a toluene/toluene-ethyl acetate=4:1 gradient. Yield:91.6 g (49.9% of theory over two stages).

Melting point 85° C.

R_(f) (SiO₂, T1 E1): 0.83

EXAMPLE 3A 1-(2-Fluorobenzyl)-1H-pyrazolo[3,4-b]pyridine-3-carboxamide

10.18 g (34 mmol) of the ester obtained in Example 2A are introducedinto 150 ml of methanol which has been saturated with ammonia at 0–10°C. The mixture is stirred at room temperature for two days and thenconcentrated in vacuo.

R_(f) (SiO₂, T1 E1): 0.33

EXAMPLE 4A 3-Cyano-1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridine

36.1 g (133 mmol) of1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridine-3-carboxamide from Example3A are dissolved in 330 ml of THF, and 27 g (341 mmol) of pyridine areadded. Then, over the course of 10 minutes, 47.76 ml (71.66 g, 341 mmol)of trifluoroacetic anhydride are added, during which the temperaturerises to 40° C. The mixture is stirred at room temperature overnight. Itis then added to 1 l of water and extracted three times with 0.5 l ofethyl acetate each time. The organic phase is washed with saturatedsodium bicarbonate solution and with 1N hydrochloric acid, dried withmagnesium sulphate and concentrated in a rotary evaporator.

Yield: 33.7 g (100% of theory)

Melting point: 81° C.

R_(f) (SiO₂, T1 E1): 0.74

EXAMPLE 5A Methyl1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridine-3-carboximidate

30.37 g (562 mmol) of sodium methoxide are dissolved in 1.5 l ofmethanol, and 36.45 g (144.5 mmol) of3-cyano-1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridine (from Example 4A)are added. The mixture is stirred at room temperature for 2 hours andthe resulting solution is employed directly for the next stage.

EXAMPLE 6A 1-(2-Fluorobenzyl)-1H-pyrazolo[3,4-b]pyridine-3-carboxamidine

The solution of methyl1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridine-3-carboximidate inmethanol obtained from Example 5A is mixed with 33.76 g (32.19 ml, 562mmol) of glacial acetic acid and 9.28 g (173 mmol) of ammonium chlorideand stirred under reflux overnight. The solvent is evaporated in vacuo,the residue is thoroughly triturated with acetone, and the precipitatedsolid is filtered off with suction. It is added to 2 l of water, 31.8 gof sodium carbonate are added while stirring, the mixture is extractedthree times with a total of 1 l of ethyl acetate, and the organic phaseis dried with magnesium sulphate and evaporated in vacuo.

Yield 27.5 g (76.4% of theory over two stages)

m.p.: 86° C.

R_(f) (SiO₂, T1 EtOH1): 0.08

EXAMPLE 7A2-[1-(2-Fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-5-[(E)phenyldiazenyl]4,6-pyrimidinediamine

3.87 g of sodium methanolate and then 12.2 g (71.7 mmol) ofphenylazomalononitrile (L. F. Cavalieri, J. F. Tanker, A. Bendich, J.Am. Chem. Soc., 1949, 71, 533) are added to a stirred solution of 21.92g (71.7 mmol) of1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridine-3-carboxamidine inN,N-dimethylformamide from Example 6A. The mixture is stirred at 110° C.overnight and allowed to cool. The solid which precipitates is filteredoff with suction and washed with ethanol. Drying results in 23 g (73% oftheory) of the target compound.

EXAMPLE 8A2-[1-(2-Fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-4,5,6-pyrimidinetriaminetrihydrochloride

5 g (11.38 mmol) of2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-5-[(E)-phenyldiazenyl]-4,6-pyrimidinediaminefrom Example 7A are hydrogenated with 800 mg of 50% Raney nickel inwater in 60 ml of DMF under a pressure of 65 bar of hydrogen at 62° C.for 22 hours. The catalyst is filtered off with suction throughkieselguhr, and the solution is evaporated in vacuo and stirred with 5Nhydrochloric acid. The yellowish brown precipitate which separates outis filtered off with suction and dried. 3.1 g (59.3% of theory) of thetargeted compound are obtained. The free base is obtained by shakingwith dilute sodium bicarbonate solution and extracted with ethylacetate. The solid insoluble in both phases is filtered off withsuction. The ethyl acetate phase also contains small amounts of the freebase.

EXAMPLE 9A Methyl cyanomethyl(methyl)carbamate

prepared in analogy to: Q. Li, D. T. Chu, A. Claiborne, C. S. Cooper, C.M. Lee, J. Med. Chem. 1996, 39, 3070–3088.

EXAMPLE 10A Sodium(E)-2-cyano-2-[(methoxycarbonyl)(methyl)amino]ethenolate

0.46 g (0.01 mmol) of sodium methoxide is added under argon totetrahydrofuran (solution A). Then 1.00 g (0.01 mmol) of methylcyanomethyl(methyl)carbamate from Example 9A is added to 1.73 g (0.02mmol) of ethyl formate. Solution A is slowly added dropwise to thismixture. The mixture is stirred at RT overnight. The solvent isconcentrated in vacuo in a rotary evaporator, and diethyl ether is addedto the residue. The crystals which have separated out are filtered offwith suction and dried under high vacuum.

Yield: 1.05 g (76% of theory).

HPLC (Method 4): R_(t)=1.35 ml.

¹H-NMR (200 MHz, DMSO-d₆): δ=2.90 (d, 1H), 3.35 (s, 3H), 3.47 (s, 3H).

EXAMPLES Example 1 Methyl4-amino-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-5-pyrimidinyl(methyl)carbamate

Under argon, 0.80 g (2.61 mmol) of1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridine-3-carboxamidine fromExample 6A, 0.51 g (2.86 mmol) of sodium(E)-2-cyano-2-[(methoxycarbonyl)(methyl)amino]ethenolate from Example10A and 0.53 g (0.73 ml, 5.23 mmol) of triethylamine are added to 50 mlof toluene. The mixture is heated under reflux for 9 hours. It is thencooled to RT again and is mixed and extracted with dichloromethane andwater. The organic phase is dried over magnesium sulphate, filtered andconcentrated in vacuo in a rotary evaporator. The residue is mixed with5 ml of diethyl ether and crystallizes therewith. The crystals arefiltered off with suction, dried and purified by preparative RP-HPLC.

Yield: 20.2 mg (2% of theory)

LC/MS (Method 2): R_(t)=3.01 min

MS (EI): m/z=408 (M+H)⁺

¹H-NMR (300 MHz, DMSO-d₆): δ=3.09 (s, 3H), 3.29 (s, 3H), 5.83 (s, 2H),7.09–7.42 (m, 5H), 8.20 (s, 1H), 8.64 (dd, 1H). 8.94 (dd, 1H), 9.27 (br.s, 2H).

Example 2 Ethyl4,6-diamino-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-5-pyrimidinylcarbamate

107.35 mg (0.31 mmol) of2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-4,5,6-pyrimidinetriaminetrihydrochloride from Example 8A are added to 5 ml of pyridine, and themixture is cooled to 0° C. 33.25 mg (0.31 mmol) of ethyl chloroformateare added, and the reaction is left to stir at RT overnight. Thepyridine is evaporated in vacuo in a rotary evaporator, and the residueis purified by preparative RP-HPLC.

Yield: 56.2 mg (43% of theory)

LC/MS (Method 1): R_(t)=2.66 min

MS (EI): m/z=423 (M+H)⁺

¹H-NMR (300 MHz, DMSO-d₆): δ=1.17–1.33 (m, 3H), 3.97–4.14 (m, 2H), 5.80(s, 2H), 6.14 (br. s, 4H), 7.07–7.17 (m, 2H), 7.22 (t, 1H). 7.29–7.40(m, 2H), 1H), 8.60 (d, 1H), 9.07 (d, 1H).

Example 3 Isopropyl4,6-diamino-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-5-pyrimidinylcarbamate

Prepared in analogy to Example 2 with 150 mg (0.43 mmol) of2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-4,5,6-pyrimidinetriaminetrihydrochloride from Example 8A, 7.5 ml of pyridine and 52.47 mg (0.43mmol) of isopropyl chloroformate. The residue is taken up in adichloromethane/methanol mixture, filtered and dried.

Yield: 165 mg (88% of theory)

LC/MS (Method 1): R_(t)=2.84 min

MS (EI): m/z=437 (M+H)⁺

¹H-NMR (300 MHz, DMSO-d₆): δ=1.26 (d, 6H), 4.82 (quin., 1H), 5.92 (s,2H), 7.07–7.20 (m, 2H), 7.25 (t, 1H). 7.31–7.43 (m, 2H), 7.47–7.57 (m,1H), 8.16 (br. s, 1H), 8.74 (dd, 1H), 8.98 (dd, 1H).

Example 4 Neopentyl4,6-diamino-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-5-pyrimidinylcarbamate

Prepared in analogy to Example 2 with 100 mg (0.29 mmol) of2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-4,5,6-pyrimidinetriaminetrihydrochloride from Example 8A, 5 ml of pyridine and 43 mg (0.29 mmol)of neopentyl chlorocarbonate.

Yield: 54 mg (41% of theory)

LC/MS (Method 1): R_(t)=3.10 min

MS (EI): m/z=465 (M+H)⁺

¹H-NMR (400 MHz, DMSO-d₆): δ=0.95 (br. s, 9H), 3.74 (s, 2H), 5.79 (s,2H), 6.10 (br. s, 4H), 7.08–7.17 (m, 2H), 7.22 (t, 1H), 7.29–7.39 (m,2H), 8.00 (br. s, 1H), 8.60 (dd, 1H), 9.06 (dd, 1H).

Example 5 Methyl4,6-diamino-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-5-pyrimidinylcarbamate

30.5 g (87.0 mmol) of2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-4,5,6-pyrimidinetriaminetrihydrochloride from Example 8A are dissolved in 30 ml of pyridine. Theresulting solution is cooled to 0° C. 8.22 g (87.0 mmol) of methylchloroformate are added, and the mixture is stirred at 0° C. for afurther 2 hours. It is subsequently allowed to warm to room temperatureand is stirred for a further 12 hours. After concentration in vacuo, theresidue is washed with water and dried. Further purification is effectedby stirring in 300 ml of boiling diethyl ether. The precipitated productis filtered off with suction and dried in vacuo.

Yield: 32.6 g (92% of theory)

LC/MS (Method 1): R_(t)=2.61 min

MS (EI): m/z=409 (M+H)⁺

¹H-NMR (400 MHz, DMSO-d₆): δ=3.61 (s, 3H), 5.80 (s, 2H), 6.19 (br. s,4H), 7.08–7.16 (m, 2H), 7.22 (t, 1H), 7.28–7.39 (m, 2H), 7.99 (br. s,1H), 8.60 (dd, 1H), 9.05 (dd, 1H).

Example 6 Ethyl4,6-diamino-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-5-pyrimidinyl(methyl)carbamate

54 mg (0.13 mmol) of ethyl4,6-diamino-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-5-pyrimidinylcarbamatefrom Example 2 are added to 5 ml of DMF, the mixture is cooled to 0° C.,and 7.67 mg (0.19 mmol) of sodium hydride are added. Then 18.14 mg (0.13mmol) of iodomethane are added dropwise, and the mixture is stirred forone hour. The mixture is mixed with water and extracted withdichloromethane. The combined organic phases are dried over magnesiumsulphate and concentrated in a rotary evaporator. The residue ispurified first by column chromatography (mobile phase:dichloromethane/methanol=10:1) and then by preparative RP-HPLC.

Yield: 32 mg (58% of theory)

LC/MS (Method 2): R_(t)=2.91 min

MS (EI): m/z=437 (M+H)⁺

¹H-NMR (200 MHz, DMSO-d₆): δ=1.08 (t, 3H), 2.99 (s, 3H), 2.93–4.11 (m,2H), 5.79 (s, 2H), 6.35 (br. s, 4H), 7.06–7.14 (m, 2H), 7.16–7.28 (m,1H), 7.28–7.32 (m, 2H), 8.59 (dd, 1H), 9.06 (dd, 1H).

Example 7 Isopropyl4,6-diamino-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-5-pyrimidinyl(methyl)carbamate

Prepared in analogy to Example 6 with 75 mg (0.17 mmol) ofisopropyl-4,6-diamino-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-5-pyrimidinylcarbamatefrom Example 3, 10.31 mg (0.26 mmol) of sodium hydride and 24.4 mg (0.17mmol) of iodomethane. The residue is purified by preparative RP-HPLC.

Yield: 32 mg (41% of theory)

LC/MS (Method 1): R_(t)=2.97 min

MS (EI): m/z=451 (M+H)⁺

¹H-NMR (300 MHz, DMSO-d₆): δ=1.09 (d, 6H), 2.98 (s, 3H), 4.80 (quin.,1H), 5.79 (s, 2H), 6.31 (br. s, 4H), 7.05–7.16 (m, 2H), 7.22 (t, 1H),7.28–7.40 (m, 2H), 8.59 (dd, 1H), 9.07 (dd, 1H).

Example 8 Methyl4,6-diamino-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-5-pyrimidinyl(methyl)carbamate

Prepared in analogy to Example 6 with 310 mg (0.76 mmol) ofmethyl-4,6-diamino-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-5-pyrimidinylcarbamatefrom Example 5, 27.32 mg (1.14 mmol) of sodium hydride and 215.5 mg(1.52 mmol) of iodomethane. The mixture is worked up by adding water and2 molar potassium hydroxide solution and extracting withdichloromethane. The combined organic phases are dried with magnesiumsulphate and concentrated in a rotary evaporator. The residue ispurified by preparative RP-HPLC.

Yield: 93 mg (29% of theory)

Larger amounts of the compound of Example 8 can be prepared by thefollowing synthetic method:

20.0 g (49.0 mmol) of methyl4,6-diamino-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-5-pyrimidinylcarbamatefrom Example 5 are dissolved in 257 ml of tetrahydrofuran and cooled to0° C. 53.9 ml (49.0 mmol of a 1M solution in tetrahydrofuran) of lithiumbis(trimethylsilyl)amide are added dropwise over the course of 15minutes. After stirring at 0° C. for 20 min, 6.95 g (53.9 mmol) ofiodomethane are added. After one hour, the mixture is allowed to warm toroom temperature, and the reaction is stopped by adding saturatedaqueous ammonium chloride solution. The phases are separated. Theaqueous phase is extracted several times with ethyl acetate anddichloromethane. The combined organic phases are concentrated in vacuo.The residue obtained in this way is suspended in a mixture ofdichloromethane and tetrahydrofuran (1:1). The insoluble crystals arefiltered off with suction and taken up in methanol. The mixture isrefluxed for one hour. After cooling, the precipitate which hasseparated out is filtered off. The red solid obtained in this way issuspended in 100 ml of a mixture of dioxane and dichloromethane (1:1)and, while boiling, 20 ml of methanol are added until a clear solutionforms. Activated carbon is added, and the mixture is boiled briefly andfiltered hot through kieselguhr. The solution obtained in this way isevaporated to dryness. The suspension after taking up in methanol isstirred at room temperature for one hour. The white crystals arefiltered off with suction.

Yield: 14.9 g (72% of theory)

LC/MS (Method 3): R_(t)=1.85 min

MS (EI): m/z=423 (M+H)⁺

¹H-NMR (200 MHz, DMSO-d₆): δ=3.01 (s, 3H), 3.57 (s, 3H), 5.92 (s, 2H),7.05.7.17 (m, 2H), 7.18–7.46 (m, 3H), 7.47–7.61 (m, 2H), 7.59–7.97 (m,2H), 8.71–8.81 (m, 1H), 8.97 (dd, 1H).

Example 9 Isopropyl4,6-diamino-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-5-pyrimidinyl(ethyl)carbamate

Prepared in analogy to Example 6 with 60 mg (0.14 mmol) of isopropyl4,6-diamino-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-5-pyrimidinylcarbamatefrom Example 3, 4.95 mg (0.21 mmol) of sodium hydride and 21.4 mg (0.17mmol) of iodoethane. To complete the reaction, the same amount of sodiumhydride and iodoethane are added once again. The residue is purified bypreparative RP-HPLC.

Yield: 43 mg (67% of theory)

LC/MS (Method 1): R_(t)=2.97 min

MS (EI): m/z=465 (M+H)⁺

¹H-NMR (200 MHz, DMSO-d₆): δ=0.96–1.06 (m, 3H), 1.09 (d, 6H), 2.79–2.93(m 2H), 4.82 (quin., 1H), 5.80 (s, 2H), 6.25 (br. s, 4H), 7.01–7.14 (m,2H), 7.15–7.50 (m, 3H), 8.60 (dd, 1H) 9.09 (dd, 1H).

1. A compound of the formula (I)

in which R¹ is —NR³C(═O)OR⁴, R² is hydrogen or NH₂, R³ is hydrogen or(C₁–C₄)-alkyl, R⁴ is (C₁–C₆)-alkyl, or a salt or hydrate thereof.
 2. Thecompound of claim 1, in which R¹ is —NR³C(═O)OR⁴, R² is hydrogen or NH₂,R³ is (C₁–C₄)-alkyl, R⁴ is (C₁–C₄)-alkyl, or a salt or hydrate thereof.3. The compound of claim 1, in which R¹ is —NR³C(═O)OR⁴, R² is NH₂, R³is methyl or ethyl, R⁴ is methyl, ethyl or isopropyl, or a salt orhydrate thereof.
 4. The compound of claim 1 having the followingstructure: methyl4,6-diamino-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-5-pyrimidinyl(methyl)carbamate

or a salt or hydrate thereof.
 5. The compound of claim 1, wherein saidcompound is methyl4,6-diamino-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-5-pyrimidinylcarbamate:

or a salt or hydrate thereof.
 6. A process for the preparation ofcompounds of the formula (I) as defined in claim 1, characterized inthat either [A] a compound of the formula (Ia)

in which R⁴ is as defined in claim 1, is reacted with a compound of theformula (II)R³—X¹  (II), in which R³ is as defined in claim 1, and X¹ is a leavinggroup, or [B] the compound of the formula (III)

is reacted with a compound of the formula (IV)

in which R⁴ is as defined in claim 1, or [C] the compound of the formula(V)

is reacted with a compound of the formula (VI)

in which R³ and R⁴ are as defined in claim 1, to give a compound of theformula (Ib)

in which R³ and R⁴ are as defined in claim
 1. 7. A pharmaceuticalcomposition comprising at least one compound of the formula (I) asdefined in claim 1, and at least one further excipient.
 8. Apharmaceutical composition comprising at least one compound of theformula (I) as defined in claim 1 in combination with at least oneorganic nitrate or NO donor.
 9. A pharmaceutical composition comprisingat least one compound of the formula (I) as defined in claim 1 incombination with at least one compound which inhibits the breakdown ofcyclic guanosine monophosphate (cGMP).
 10. A method for the treatment ofhypertension, comprising administering to a patient in need thereof atherapeutically effective amount of a compound of claim
 1. 11. A methodfor the treatment of sexual dysfunction, comprising administering to apatient in need thereof a therapeutically effective amount of a compoundof claim
 1. 12. The method of claim 10 or 11, where compounds of theformula (I) as defined in claim 1 are employed in combination with atleast one organic nitrate or NO donor or in combination with at leastone compound which inhibits the breakdown of cyclic guanosinemonophosphate (cGMP).
 13. The method of claim 11, wherein the sexualdysfunction is erectile dysfunction or female sexual dysfunction.